Attempts have been made to obtain a blended resin composition having the characteristic properties of both polyolefin and polyamide for the purpose of improving the mechanical properties, heat resistance, and dyeability of polyolefin, and reducing the water absorption of polyamide, and thereby avoiding the deterioration of physical properties of polyamide caused by water absorption. This object is not achieved by merely blending polypropylene and polyamide by melt-mixing. Mere blending provides a mixture which is subject to phase separation and is poor in surface gloss and mechanical strength, because polypropylene and polyamide mix poorly. A known way to improve their compatibility is to partly or entirely modify a polyolefin with an unsaturated carboxylic acid anhydride. In addition, there is proposed a composition containing a modified polyolefin to which metal atoms are attached. (Japanese Patent Laid-open Nos. 167740/1981 and 74143/1984)
The modified polyolefin to which metal atoms are attached is improved in compatibility to some extent but is not sufficiently improved in mechanical strength, because it is formed by reacting an acid-modified polyolefin with a metal compound.